Non-pneumatic, ground-engaging cushioning means with raised treads for tires or endless tracks

ABSTRACT

A tire comprising a body constructed to deform resiliently under load and a tread provided on the body. The tread comprising a plurality of raised portions (29) disposed in circumferential relationship and defining grooves (49) therebetween. Each raised portion (25) comprising a first central section (27) and a pair of lateral sections (29) each extending outwardly from the central section towards one side of the body. The lateral sections (29) define a V formation and the first central section (27) extends from the V formation in a direction away from the outer ends of the lateral sections (29) and towards the V formation if the next adjacent raised portion. The body may be defined by a plurality of segments (11) individually mountable onto a base.

FIELD OF THE INVENTION

This invention relates to a ground engaging means for vehicles and isparticularly suitable as a tire or endless track for work vehicles ofthe skid-steer type.

BACKGROUND OF THE INVENTION

A skid-steer vehicle is self-propelled vehicle which has drive wheels ortracks on two opposed sides of the vehicle and which achieves a steeringfunction by controlled rotation of one of the opposed drive wheels ortracks relative to the other. Relative rotation between the opposeddrive wheels or tracks results in a change in direction of the vehicleand so provides a steering function. With such vehicles it is importantthat the drive wheels or tracks each have a tread formation thatprovides good traction with the ground and good directional control bothin straight-line travel and in turning.

SUMMARY OF THE INVENTION

The present invention seeks to provide a ground engaging means having atread formation which provides good traction with the ground and gooddirectional control.

In one form the invention resides in a ground engaging means comprisinga body constructed to deform resiliently under load and a tread providedon the body, the tread comprising a plurality of raised portionsdisposed in circumferential relationship and defining groovestherebetween, each raised portion comprising a first central section anda pair of lateral sections each extending outwardly from the centralsection towards one side of the body, the lateral sections defining a Vformation and the first central section extending from the V formationin a direction away from the outer ends of the lateral sections andtowards the V formation of the next adjacent raised portion.

Preferably, the end of each first central section remote from thelateral sections converges to a point.

The first central section of each raised portion may include a pair ofgenerally parallel edges and a pair of converging edges which definesaid point. For preference, each of the converging edges is generallyparallel with a respective one of the lateral sections.

Each raised portion may also include a second central section extendingfrom the V formation in a direction opposite to the first centralsection.

The end of each second central section remote from the lateral sectionsmay define a tail formation having a recess.

The outer ends of each pair of lateral sections preferably eachterminate adjacent the respective side of the body.

In one arrangement, the body is annular such that the ground engagingmeans is in the form of a tire. For preference, the annular body is ofone-piece construction. In such a case, the first and second centralsections may co-operate to form a central rib which extends around thebody.

In another arrangement, the body is defined by a plurality of segmentsindividually mountable onto a base. Where the ground engaging means isfor a wheel, the base may be of any suitable form such as the rim of thewheel or a band adapted to be permanently or removably fitted onto therim. Where the ground engaging means is for an endless track, the basemay comprise a flexible endless band passing around end rollers of thetrack.

Preferably, each segment is configured in a V formation. For preferencethe V formation defined by the segment generally corresponds to the Vformation defined by the lateral sections of the raised portion of thetread.

Each segment is preferably hollow. Conveniently, the segment is tubularand is open at its ends.

In another form the invention resides in a ground engaging segmentcomprising a hollow elongated body having an inner longitudinal face, anouter longitudinal face and longitudinal side faces extending betweenthe inner and outer faces, a raised portion provided on the outer face,at least part of said raised portion being spaced inwardly of thelongitudinal side faces, said raised portion comprising central sectionand a pair of lateral sections each extending outwardly from the firstcentral section towards the ends of the body, the lateral sectionsdefining a V formation and the first central section extending from theV formation in the direction away from the outer ends of the lateralsections and towards the adjacent longitudinal side face of the body.

The end of the first central section remote from the lateral sectionspreferably converges to a point. The point defined by the centralsection may include a pair of converging edges which are generallyco-planar with the corresponding longitudinal side face of the body.

Each raised portion may include a second central section extending fromthe V formation in a direction opposite to the first central section.

The end of each second central section remote from the lateral sectionsmay define a tail formation having a recess. The tail formation mayinclude a pair of diverging edges which are generally co-planar with thecorresponding longitudinal side face of the body.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be better understood by reference to the followingdescription of several specific embodiment thereof as shown in theaccompanying drawings in which:

FIG. 1 is a perspective view of a tire constructed in accordance with afirst embodiment;

FIG. 2 is a perspective view of a segment which forms part of the tireof FIG. 1;

FIG. 3 is a perspective view from the underside of the segment of FIG.2;

FIG. 4 is a perspective view of a tire according to a second embodiment;

FIG. 5 is a perspective view of a tire constructed in accordance with athird embodiment;

FIG. 6 is a perspective view of a segment which forms part of the tireof FIG. 5 and

FIG. 7 is a perspective view from the underside of the segment of FIG.6.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The embodiments shown in the drawings are directed to tires for use onvehicles of the skid-steer type.

The embodiment shown in FIGS. 1 to 3 of the drawings is in the form of atire comprising a plurality of ground engaging segments 11 adapted to beindividually mounted on the periphery of a wheel rim (not shown) to forma wheel.

Each segment extends transversely of the direction of travel of thewheel and is configured into a V formation, as shown in the drawings.

Each segment 11 comprises a hollow body 13 formed from reinforced,resilient polymeric material such as rubber. The body is tubular andopen at its ends to define apertures 15 which provide access to theinterior of the hollow body for air or mounting means. A ventilationcavity 16 extends between apertures 15.

The hollow body of each ground engaging segment comprises an innerlongitudinal face 17 for engagement against the rim, an outerlongitudinal face 19 for contacting the ground and two longitudinal sidefaces 21, 22 extending between the inner and outer faces. Thelongitudinal body further includes end faces 23 in which the apertures15 are provided.

It has been found that the relationship between the height of thesegment (defined as the distance between the inner longitudinal face 17and the outer longitudinal face 19) and the width of the segment(defined as the distance between the longitudinal faces 21 and 22)influences the load carrying and torque transfer capabilities of thetire. Although any suitable ratio of height to width may be utilized, ithas been found that ratios in the range 0.75 to 1.1 (height:width)exhibit desirable load carrying and torque transfer characteristics.

The outer longitudinal face 19 is provided with a raisedground-contacting portion which includes a first central section 27 andtwo lateral sections 29, all of which are formed integrally with eachother. The lateral sections 29 extend outwardly from one end of thecentral section towards respective end faces 23 and define a V formationwhich corresponds to the V formation defined by the segment. Eachlateral section 29 has longitudinal edges 31 spaced inwardly from thelongitudinal side faces 21, 22 of the body so as to define rebates 33 inthe body.

As can be seen in FIGS. 2 and 3, raised ground-contacting portion 25overlies a raised central portion of apertures 15. As is also apparentfrom the tubular nature of the segment bodies 13, cavities 16 also havea raised central portion.

The central section 27 extends from the base of the V formation definedby the lateral sections 29 to the adjacent longitudinal face 21 of thehollow body, as shown in the drawings. The central section 27 includes apair of parallel side edges 37 and a pair of converging edges 39 whichdefine a point 40. The converging edges 39 are co-planar with thelongitudinal side 21 of the hollow body.

The segments are mounted circumferentially on the rim with neighboringlongitudinal faces confronting one another. The segments are secured tothe rim by means of a clamping plate (not shown) located within thecavity 16 in each segment. The clamping plate is secured to the rim byway of fixing bolts which extend through apertures in the clamping plateand corresponding apertures 45 formed in the inner longitudinal face 17of the segment. The clamping plate has longitudinal sides which areupturned in a curved formation so as to provide some lateral support forthe longitudinal side faces of the hollow body and also to avoidpresenting a sharp edge which might damage the hollow body.

Thus mounted, on a rim or base, the segments cooperate to provide a tirebody which is resiliently deformable under load. As the segments deform,raised tread portion 25 moves radially inwardly, so that ground-engagingloads are directed laterally of the ventilation cavity 16 to confrontinglongitudinal faces 21, 22 which can pass these loads to neighboringelements.

With the segments mounted circumferentially on the rim, the raisedportions 25 are in circumferentially spaced relationship and grooves 49are defined by co-operation between the neighboring rebates 33 ofadjacent segments.

Referring now to FIG. 4 of the drawings, tire according to the secondembodiment is similar to the first embodiment with the exception that itis of one-piece construction rather than being formed from a pluralityof segments which are assembled onto a wheel rim. In this embodiment,the tire is in the form of an annular body which can be fitted onto awheel rim and retained in such position by way of clamping plates as wasthe case in the first embodiment or any other suitable way such as bybonding.

In a similar fashion to the first embodiment, it has been found that the"height to width" ration of this one-piece construction plays animportant role in determining the load carrying and torque transfercharacteristics of the tire. In this case however the "width" would bedefined as the annular inner face circumference of the tire divided bythe number of cavities (effectively giving the equivalent segment widthas in the first embodiment).

As was noted in the first embodiment, it has been found that ratios inthe range of 0.75 to 1.1 (height:width) exhibit the most desirable loadcarrying and torque transfer characteristics, although any desirableratio may actually be used.

The third embodiment, which is shown in FIGS. 5, 6 and 7 is similar tothe first embodiment, which the exception that each raised portion 25further includes a second central section 51 which extends from the baseof the V formation defined by the two lateral sections 29 in theopposite direction to the first central section 27. The free end of thesecond central section (being the end remote from the lateral sections29) defines a tail formation 53 having a recess 55. The tail formation53 has a pair of diverging edges 57 which define the recess 55 and whichare co-planar with the longitudinal side 22 of the body. The recess 55generally conforms with, and receives, the point 40 of a neighboringsegment, as shown in FIG. 5.

The first and second central sections 27 and 51 co-operate to form acentral circumferential rib on the tire which is conducive to smoothride conditions on paved and other hard surfaces.

The various embodiments each provide a tire which is of relativelysimple construction but which is highly effective in operation on askid-steer vehicle. The tread of the tire provides for good tractionwith the ground and directional control both in straight-line travel andturning. The tire has further benefits in that it is resilient so as toprovide cushioning and that it is non-pneumatic thereby avoidingproblems with puncturing.

In summary, the invention provides, in one aspect a hollow, resilient,integral, ground-engaging, cushioning segment for a wheel or endlesstrack for a vehicle, said wheel or endless track having a band-shapedbase cyclically movable around at least one axis, multiple saidcushioning segments being mountable in a side-by-side, closelyinterfitting disposition around said base to provide a continuousground-engaging support cushion for said vehicle, individual saidcushioning segments being elongated, tubular and open-ended to define atleast one longitudinally extending aperture providing interior access tosaid hollow segment, said cushioning segments extending across saidband-shaped base between segment ends at opposed sides of said band,when mounted on said base, and each comprising:

a) a longitudinal inner portion for engagement with said base;

b) a longitudinal outer segment portion carrying a ground-engagingsurface;

c) longitudinal side faces extending between said inner and outer facesand providing resilient support for said outer segment portion;

d) a longitudinally extending raised tread carrying said ground-engagingsurface, said raised tread being located on said outer segment portionbetween and spaced from said hollow segment; and

e) said at least one longitudinally extending ventilation aperture, saidaperture being defined between said inner, outer and side portions andopening to atmosphere at each said segment end to cool saidground-engaging segment;

wherein said ventilation aperture has a cross-sectional shape includinga raised portion extending beneath said raised tread along said treadwhereby, under ground-engaging loads, said tread-bearing portion ismovable inwardly toward said inner portion and said ground-engagingloads are directed laterally of said side walls toward neighboringsegments and wherein said cushioning segments are configured to beinter-fittable around said at least one axis, with said segment, saidtread and said ventilation aperture being shaped to extend laterallytoward a neighboring segment, when mounted, said shaping beingsymmetrical about a midpoint of each segment's length.

It should be appreciated that the scope of the invention is not limitedto the scope of the embodiments described.

I claim:
 1. A hollow, resilient, integral, ground-engaging, cushioningsegment for a wheel or endless track for a vehicle, said wheel orendless track having a band-shaped base cyclically movable around atleast one axis, multiple said cushioning segments being mountable in aside-by-side, closely interfitting disposition around said base toprovide a continuous ground-engaging support cushion for said vehicle,individual said cushioning segments being elongated, tubular andopen-ended to define at least one longitudinally extending apertureproviding interior access to said hollow segment, said cushioningsegments extending across said band-shaped base between segment ends atopposed sides of said band, when mounted on said base, and eachcomprising:a) a longitudinal inner portion for engagement with saidbase; b) a longitudinal outer segment portion carrying a ground-engagingsurface; c) longitudinal side faces extending between said inner andouter faces and providing resilient support for said outer segmentportion; d) a longitudinally extending raised tread carrying saidground-engaging surface, said raised tread being located on said outersegment portion between and spaced from said side faces and defining atread-bearing portion of said hollow segment; and e) said at least onelongitudinally extending ventilation aperture, said aperture beingdefined between said inner, outer and side portions and opening toatmosphere at each said segment end to cool said ground-engagingsegment;wherein said ventilation aperture has a cross-sectional shapeincluding a raised portion extending beneath said raised tread alongsaid tread whereby, under ground-engaging loads, said tread-bearingportion is movable inwardly toward said inner portion and saidground-engaging loads are directed laterally of said side walls towardneighboring segments and wherein said cushioning segments are configuredto be interfittable around said at least one axis, with said segment,said tread and said ventilation aperture being shaped to extendlaterally toward a neighboring segment, when mounted, said shaping beingsymmetrical about a midpoint of each segment's length.
 2. Aground-engaging segment according to claim 1 wherein said hollow segmenthas an interior cavity and said ventilation aperture is dimensioned toprovide access to said interior cavity to fit mounting hardware.
 3. Aground engaging means according to claim 2 wherein said raised portionsare in a circumferentially spaced relationship one with another andgrooves are defined between said raised portions.
 4. A ground engagingmeans according to claim 2 wherein said end of each first centralsection remote from said lateral sections converges to a point.
 5. Aground engaging means according to claim 1 wherein each raised portionincludes a second central section extending from said V formation in adirection opposite to said first central section and wherein each secondcentral section remote from said lateral sections defines a tailformation having a recess.
 6. A ground-engaging segment according toclaim 2 having mounting apertures extending through said longitudinalinner portion, in combination with mounting hardware comprising aclamping plate insertable within said interior cavity and fixing meansfor said clamping plate to extend through said mounting apertures andsecure said segment to said base.
 7. A ground-engaging segment accordingto claim 1 wherein said segment, said tread and said ventilationaperture are V-shaped with a peak centrally disposed with regard to saidmidpoint of each segment's length when viewed in a direction transverseto said at least one axis.
 8. A ground-engaging segment according toclaim 7 wherein said ventilation aperture cross-sectional shape has sideregions cooperating one with each said longitudinal side face to definea side wall having a reduced thickness zone of deformation under load,and said ventilation aperture is dimensioned to provide access into saidhollow segment.
 9. A ground-engaging segment according to claim 7wherein said treads provide a rolling ground-engaging surface andwherein said V-shaped treads each have a symmetrically disposednose-like portion extending away from said peak toward a neighboringelement to increase the continuity of said rolling ground-engagingsurface.
 10. A ground-engaging segment according to claim 7 havingrebates along each side of said tread, adjacent rebates of neighboringtreads cooperating to provide grooves, said grooves enhancing tractionin soft ground.
 11. A ground-engaging segment according to claim 10wherein said rebates define corners with said ground-engaging surfacecarried by said tread and said tread and ground-engaging surface extendlaterally of said segment length around said at least one axis toprovide a non-deforming, load-bearing support structure during groundengagement.
 12. A ground-engaging segment according to claim 11 whereinsaid side faces are flat and meet said inner portion at inner cornersand wherein said inner portion has an inner surface between saidcorners, said inner surface being shaped to conform to said base.
 13. Aground-engaging segment according to claim 12 wherein said ventilationaperture or apertures have, viewed endwise, a cross-sectional aperturewith a shape extending along said inner portion, along said side facesto define side walls and between said side walls to define a raisedcentral portion.
 14. A ground-engaging segment according to claim 13wherein said raised central portion is a V-shaped peak and said outersegment portion of said ground-engaging segment also has a V-shapedconfiguration and is urged to spread under ground-engaging loads to urgesaid sidewalls apart.
 15. A ground-engaging segment according to claim14 wherein said side faces are flat and meet said outer segment portionat outer corners.
 16. A ground-engaging segment according to claim 7,wherein said raised portion comprises a first central section and a pairof lateral sections each extending outwardly from said first centralsection toward said ends of said body, said lateral sections defining aV formation and said first central section extending from said Vformation in said direction away from said outer ends of said lateralsections and towards said adjacent longitudinal side of said body.
 17. Aground engaging segment according to claim 16 wherein said end of saidcentral section remote from said lateral sections converges to a point.18. A ground engaging segment according to claim 16 wherein said raisedportion includes a second central section extending from said Vformation in a direction opposite to said first central section andwherein said end of each second central section remote from said lateralsections defines a tail formation having a recess.
 19. A ground engagingsegment according to claim 16 wherein said body is configured in a Vformation and wherein said V formation defined by said body generallycorresponds to said V formation defined by said lateral sections.
 20. Aground engaging segment according to claim 19 wherein the V formationdefined by said body generally corresponds to the V formation defined bysaid lateral sections.
 21. A hollow, resilient, integral,ground-engaging, cushioning segment for a wheel or endless track for avehicle, said wheel or endless track having a band-shaped basecyclically movable around at least one axis, multiple said cushioningsegments being mountable in a side-by-side, closely interfittingdisposition around said base to provide a continuous ground-engagingsupport cushion for said vehicle, individual said cushioning segmentsbeing elongated, tubular and open-ended to define at least onelongitudinally extending aperture providing interior access to saidhollow segment, extending across said band-shaped base between segmentends at opposed sides of said band, when mounted on said base, andcomprising:a) a longitudinal inner portion for engagement with saidbase; b) a longitudinal outer segment portion carrying a ground-engagingsurface; c) longitudinal flat side faces extending between said innerand outer faces and providing resilient support for said outer segmentportion, said side faces meeting said inner and outer faces at inner andouter corners respectively, said inner portion having an inner surfacebetween said corners, said inner surface being shaped to conform to saidbase; d) a longitudinally extending raised tread carrying saidground-engaging surface, said raised tread being located on said outersegment portion between and spaced from said side faces and defining atread-bearing portion of said hollow segment; and e) said at least onelongitudinally extending ventilation aperture, said aperture beingdefined between said inner, outer and side portions and opening toatmosphere at each said segment end to cool said ground-engaging segmentsaid ventilation aperture or apertures having, when viewed endwise ofsaid cushioning segment, a cross-sectional aperture shape extendingalong said inner portion, along said side faces to define side walls andbetween said side walls to define a raised aperture portion extendingbeneath said raised tread along said tread;wherein said segment, saidtread and said ventilation aperture are symmetrically V-shaped with apeak centrally disposed with regard to a midpoint of each segment'slength when viewed in a direction transverse to said at least one axis,said V shaping extending laterally toward a neighboring segment, whensaid segments are mounted; and wherein said cushioning segments areconfigured to be interfittable around said at least one axis; whereby,under ground-engaging loads, said tread-bearing portion is movableinwardly toward said inner portion and said ground-engaging loads aredirected laterally of said side walls toward neighboring segments.